A military official in Libya says three soldiers have been killed in clashes in the restive southern city of Sabha, a stronghold for former loyalists of late dictator Moammar Gadhafi.

The official said four soldiers were wounded in the clashes that continued for the second day Saturday after an earlier truce failed. The clashes were sparked by revenge attacks between the African-origin Tabu tribe and the Arab-origin Awlad Soliman.

The official said assailants attacked at least two military bases in the city. He spoke on condition of anonymity because he wasn't authorized to brief journalists.

Earlier this week, fighting in Sabha killed 31 people. The city was one of the last to fall under rebel control during Libya's 2011 civil war.